In text messages to supporters this month, U.S. Sen. Cory Gardner’s re-election campaign solicited funds not only to help Gardner win in November but also for Trump’s re-election campaign.

“Your contribution will benefit Cory Gardner for Senate and Trump’s Make America Great Again Committee,” reads Gardner’s fundraising page.

The split is 15% for Trump and 85% for Gardner, meaning for every $100 donation raised by Cory Gardner for Senate, Trump’s Make America Great Again Committee (MAGAC) gets $15.

Why would Gardner be raising funds for Trump? You might think Trump would raise money for Gardner simply because Gardner needs every dime he can get.

Gardner didn’t return a call asking that question, but experts say Gardner is likely using Trump’s popularity among Republicans in Colorado to boost his own fundraising results. Hence the big photo of Trump appears on the donation page–and the relatively small percentage of the money that goes to Trump’s MAGAC.

“Since it’s Gardner’s campaign sending the email and getting most of the money, I assume they think this will actually raise them more money than an appeal that doesn’t benefit Trump at all (or they have an agreement with the Trump campaign/RNC to make the same appeal),” said Andrew Mayersohn, a researcher at OpenSecrets.org, which tracks money in U.S. politics.

Trump’s MAGAC is a joint fundraising committee (JFC) that splits the money it receives between the Republican National Committee (RNC) and the Trump Campaign. JFC’s are created by two or more entities, which share fundraising costs and proceeds.

“What’s going on is that Trump MAGA and Gardner have created this WinRed page that splits contribution between them, rather than creating a new JFC and registering it with the FEC,” wrote Mayersohn. “So there are two levels of contribution splitting — first, WinRed allocates the contributions to Gardner and Trump MAGA, and then Trump MAGA splits its contributions between the Trump campaign and the RNC. It’s pretty common for campaigns to use WinRed or [for Democratic candidates] ActBlue this way, it’s just that the beneficiaries are not usually themselves JFCs.”

Trump has established JFCs to raise money with members of Congress, including vulnerable senators. As perhaps the most vulnerable senator, however, Gardner’s weakness in recent polls may be hurting his ability to leverage national advertising money. Recent multi-state ad purchases by the Trump campaign and McConnell’s Senate Leadership Fund have notably left out Colorado.